TORONTO -- Blue Jays third baseman Brett Lawrie will be out until at least the beginning of September because of a strained oblique muscle.

Lawrie, who was placed on the 15-day disabled list, is expected to miss the next three-to-four weeks with the injury. Best-case scenario would see him return around the time rosters expand on Sept. 1, while worst case would see Lawrie back at the tail end of the season. He was replaced on the active roster by southpaw Rob Rasmussen.

The news is yet another blow to a player who already missed six weeks because of a fractured right index finger. It's also the third time he's sustained an oblique injury during the past three seasons.

"You just don't know how he is going to recovery, how strong he's going to feel," general manager Alex Anthopoulos said. "Everybody recovers at their own pace, but certainly Brett is going to be out for a while."

Lawrie's oblique issue came on Tuesday, the same day he was activated from the 15-day disabled list. He felt some discomfort in his lower back during batting practice and was later removed from Tuesday night's game after the third inning when the tightness didn't go away.

The 24-year-old went for an MRI the following day and the results were sent to Florida so they could be compared with his previous results from 2012.

Some injuries cannot be avoided, but the amount of time Lawrie has spent on the DL over the past several years has to be a concern. In the past three years alone he has dealt with problems to his back, calf muscle, ankle and hands. He yet to appear in more than 125 games in a season.

"Some of this stuff was freaky -- he got by a pitch, slid into a base and rolled his ankle," Anthopoulos said. "Those are things you can't prepare for. But at some point you start having a large enough sample size, and body of work, you have to try to build in that depth to protect yourself if you know that the likelihood is someone is going to miss two weeks or three weeks.

"I don't know yet. This is Brett's third year, full year, but it's something that you have to take a step back and see."

With the exception of three innings on Tuesday night, Lawrie hasn't played since June 22. He is hitting .247 with 12 homers and 38 RBIs in 70 games this season, and his loss will be felt not only in the field but also in a lineup that struggles against left-handed pitching.

"Other than just what he brings in terms of the defense, the energy, the right-handed bat was so big as well," Anthopoulos said. "We're down a right-handed bat, and if we can find someone along the way in the next three weeks we'll look to do that as well."